Protists

eukaryotic organisms that cannot be classified as fungi, plants, or animals. Most are unicellular Offer clues about the evolution of fungi, plants, and animals /Summaries/Protists.htm /Summaries/Protists.htm

Reproduction Asexual Reproduction: gametes- reproductive cells required during sexual reproduction. *haploid cells that join together to form a diploid zygote. Protists can reproduce asexually by binary fission, budding, and fragmentation. Protists can also reproduce sexually by fusion of gametes.

Types of Asexual Reproduction Binary fission- occurs when a unicellular organism reproduces by splitting in half after replicating its DNA. Budding- a form of asexual reproduction in which part of the parent organism pinches off and forms a new organism. Fragmentation- part of a multicelluar organism breaks off and starts a new organism. **the difference between budding and fragmentation is that fragmentation can occur on accident, budding is performed by the organism itself.

Sexual Reproduction Zygospore- secretion from the zygote that provides a tough outer coating allowing the zygote to survive freezing, drying, and UV radiation. Sexual Reproduction in Unicelluar Protists- a haploid cell divides by binary fission to produce haploid cells. Two gametes fuse to form a diploid zygote, which becomes a zygospore. Sexual Reproduction in Multicellular Protists: Alternation of generations- within the life cycle of an organism, the occurrence of two or more distinct forms that differ from each other in method of reproduction. diploid, spore producing phase = sporophyte generation. haploid, gamete producing phase = gametophyte generation.

Classifying Protists *the classification of organisms currently grouped in the kingdom Protista is likely to change as scientists learn more about how these organisms are related to each other and to members of other kingdoms. molecular studies suggest that protists could be classified into up to 20 kingdoms. the characteristics that protists share with plants, animals, and fungi provide information about the evolution of these organisms.

Grouping Protists Grouping protists by the way they obtain nutrients helps us understand the ecological roles. Group by source of nutrition. 3 Groups: 1.Photosynthesis (plant-like) 2.Heterotrophic (animal-like) 3.Absorb from environment (funguslike)

Animal-like Protists Ingest other organisms to obtain energy. 1.Amoeboid – Pseudopodia – extension of cell that functions in food ingestion and movement. 2.Ciliates – Cilia – short, hair-like structures that aid in movement. 3.Flagellates – Flagella – whip-like structure that aids in movement. 4.Sporozoans – Form spore-like cells when they reproduce – Do not move – Parasitic and cause disease

Plant-like Protists Plant-like protists obtain energy from the sun. 1.Diatoms – Unique double shells 2.Euglenoids – Have one or two flagella Example: Euglena 3.Dinoflagellates – Spin through the water with their two flagella 4.Red Algae – Found in warm ocean waters – Grow at greater depths 5.Brown Algae – Large Kelp 6.Green Algae – Make up most marine kelp

Funguslike Protists Funguslike Protists absorb nutrients from their environment and reproduce by releasing spores. 1.Slime Molds – Plasmodium – the multinucleate cytoplasm of a slime mold that is surrounded by a membrane and moves as a mass 2.Water Molds and Downy Mildews – Decompose dead organisms – Parasites of aquarium fish – One type of water mold caused the 1846 potato famine in Irelad – One type of downy mildew almost wiped out the wine industry in France in 1879

Protists and Disease Protists cause a number of human diseases, including giardiasis, amebiasis, toxoplasmosis, trichomoniasis, cryptosporidiosis, Chagas disease, and malaria.

Giardiasis Infectious agent: Giardia intestinalis Transmission: Drinking water or recreational water. Symptoms: Diarrheal disease. Fact: – Affect 1/3 of the world’s developing population.

Amoebic Dysentery Infectious agent: Amoeba: Entoamoeba histolytica (found in feces) Transmission: Eating cysts in contaminated food or water; person to person contact. Symptoms: Fever, nausea, mild diarrhea, vomiting. Pain in upper right portion of abs. Facts: – 40, 000 – 100,000 people die annually (world). – Most common symptom is diarrhea

Toxoplasmosis Infectious agent: Toxoplasma gondii. Transmission: eating infected meat, feces of a cat, mother-fetus. Symptoms: mild flu-like illness, muscle aches, etc. for a month or longer. Affects heart, liver, inner ears and eyes. Facts: – 1/3 of world population carries a toxoplasmic infection – Toxoplasmosis is not harmful to healthy people, people with immune deficiencies are at risk.

Trichomoniasis Infectious agent: Trichomonas vaginalis Transmission: STD (STI) Symptoms: Inflammation of cervix, urethra. Itching/burning. Discomfort during urination. Facts: – Most common curable STD. – Causes pre-mature birth/low birth weight.

Cryptosporidiosis Infectious agent: Cryptosporidium muris (and other Cryptosporidium) Transmission: contaminated water/food. Undercooked food, cross-contaminated. Symptoms: stomach pain, diarrhea (2-10 of infection) Facts: – 10% of people in developing countries – 1993 in Milwaukee 100 deaths due to this parasite

Chagas Disease Infectious agent: Trypanasoma cruzi Transmission: Triatomine bug (Kissing bug), blood transfusions Symptoms: fever, swelling around bite site, fatigue, diarrhea, vomiting. Facts: – No vaccine – Can cause rhythm abnormalities and sudden death.

Malaria Infectious agent: Plasmodium falciparum Transmission: bite from anopholes mosquito (female) Symptoms: fever, chills, headache, coma/death. Facts – Children and pregnant women at higher risk – 3.3 billion are susceptible to malaria – Some forms will not show for 4 years after infection